Finally, is there any reason to prefer the factotum way rather than the linux's
way just with ssh-keygen (with a passphrase) + ssh-copy-id + (linux's)
ssh-agent?
All my keys are stored in several secstores ... on the net, not on my local machine.
This is even better than having lots of $HOME/.ssh files on every machine,
although of course for Linux purposes, I have some of those as well.